10 Best Boat Trailer Lights AWESOME Review and Rating

How To Troubleshoot and Fix Boat Trailer Lights that Don't Work

You plug in your trailer lights every time to test them before you tow your boat, right? What happens if they don't blink when they're supposed to? Or, worse, they blink when they're not supposed to. We're going to show you how to troubleshoot them and fix what's wrong.

First, you want to physically disconnect the tow vehicle from the trailer, including the chains. Otherwise you may be masking a ground problem, which we'll get to in a minute. The next step is to plug a tow vehicle tester light into your vehicle's connector. You can get these for as little as $10 online. If the tester shows a problem, you know it's with the vehicle, not with the trailer. Note the trailer wire color code. White is ground. Brown is the taillights. Green in the right turn and brake light. You can remember that green has an "r" in it for right. Yellow is the left turn and brake light. And you can remember that because yellow has an "l" in it for left. If the tester says the vehicle's lights are OK, the problem is with the trailer. But before we go any further, we're going to clean these contacts off with a little bit of emery board or sandpaper. And we're going to squirt some contact cleaner. And finally, apply a little dielectric grease. Now we'll try it again. Still no luck? Might just be a bulb burned out. We're going to remove the bulb, clean these contacts in here with the back of a pencil eraser or some sandpaper, spray with a little contact cleaner. We'll put a little dielectric grease on the back of the new bulb, put it back in, and try it. If you still can't get the lights to come on, especially if it's just one side of the trailer, it may be a break in the wiring. Follow each wire and look for a break or damage. On my trailer, the wires run inside the frame, and we can't see every inch of it. If you can't find a break in the wire or you're not sure, you're going to need to run a jumper wire. What we've done, the other end of this wire is connected to the green wire at the front of the trailer. We've connected this to one end of our meter, the other end of the meter is here. We'll check for continuity on this green wire. And there we go. We have continuity, so we know this wire is good. You can check each wire the same way until you find a wire that's not good. If you find a break in the wire, cut it and use a heat-shrink connector to repair it. If the lights are dim or there's other strange stuff going on, like the brake lights flashing when the turn signal is on or they only work sometimes, that may be a ground problem. We're going to take the ground strap off here and see if that fixes it. Find the ground screw on the trailer. It's almost always a white wire. We're going to take it off, clean it with a little sandpaper or emery board, spray it with some contact cleaner, and put a little dielectric grease for good contact. So now the next time your trailer lights act up you'll know what to do, and you won't have to pay someone else to do it.